Application Development Blog Posts
Learn and share on deeper, cross technology development topics such as integration and connectivity, automation, cloud extensibility, developing at scale, and security.
cancel
Showing results for 
Search instead for 
Did you mean: 
jrgkraus
Active Contributor
Being a long-time ABAPer who started up in the early 90's, regular expressions are not part of my DNA. It is some sort of monster, ugly, dangerous and mysterious.

Then, I learned about the benefits of REGEX search and replace in the ABAP editor. Did you ever replace ' +' with ' '? You know what I mean. This made me change my mind on a certain scale, and I found myself googling about REGEX to do more sophisticated search/replace in the editor.

Recently, the ABAP language developers added a set of REGEX-armed functions such as the function matches. I must say, I rarely used them, meanly caused by bad readability. Who wants to read something like
IF  matches( val = itf_wa-tdline regex = `<DS:([^>]+)>.+` ).

when reviewing source code?

However, refactoring an old program, I stumbled across the lines:
if lv_ilart = 'REP' or
lv_ilart = 'UMR' or
lv_ilart = 'MAW'.

and reasoned about how to avoid the need of writing three times lv_ilart. In an SQL statement, I could write
where ilart in ('REP', 'UMR', 'MAW')

but how do I do in an IF? Some penetrant voice inside my head kept on whispering "Use a REGEX". "No!" said I "nobody will understand it...", but the voice said: "Why don't you try?".

After some googling about REGEX and writing some dummy code for testing it out, I arrived at
if matches( val = lv_ilart regex = 'REP|UMR|MAW' ).

Leaning back for a minute and staring at this line, I had to admit, that this could be understandable to a reader. So, if I keep my REGEX simple, it could be a good idea to use this feature.

But what about the more complicated cases? REGEX is a standard in programming, and it is very powerful. How could I use this and keep the code readable?

Mi approach is: put a complex REGEX operation into a small method whose name explains the purpose. For example, instead of writing:
if matches( val = test regex = '.+\_[0-9][0-9]' ).

I would prefer to write
if has_two_numbers_suffix( filename ).
(...)

method has_two_numbers_suffix.
result = xsdbool( matches( val = in regex = '.+\_[0-9][0-9]' ) ).
endmethod.

Now, a reviewer understands what's supposed to be going on. Even if he's not able to decipher the REGEX, at least he knows what it should do.

 
7 Comments
Labels in this area